scholarly journals An Efficient Synthesis of Aryl-Substituted Pyrroles by the Suzuki–Miyaura Coupling Reaction of SEM-Protected Pyrroles

Molecules ◽  
2019 ◽  
Vol 24 (8) ◽  
pp. 1594 ◽  
Author(s):  
Keli Cui ◽  
Meng Gao ◽  
Hongyi Zhao ◽  
Dongfeng Zhang ◽  
Hong Yan ◽  
...  
Keyword(s):  
Coupling Reaction ◽  
Coupling Reactions ◽  
Protecting Group ◽  
Reaction Conditions ◽  
Cross Coupling Reactions ◽  
Wide Range ◽  
Synthetic Utility ◽  
Substituted Pyrroles ◽  
Metal Catalyzed ◽  
By Products

An efficient arylation of SEM-protected pyrroles by the Suzuki–Miyaura coupling reaction has been developed. The reaction can be carried out under mild conditions to provide aryl-substituted pyrroles in moderate to excellent yields. The scope and limitations of the methodology were evaluated, and the reaction was tolerant of a wide range of functionalities. Compared to the reported methods, the protocol has some advantages, such as commercially available materials, no debrominated by-products being formed, and the amine-protecting group being stable under the reaction conditions. The synthetic utility of the product has also been demonstrated, with several common transformations of the aryl-substituted pyrrole product being conducted. This protocol will offer the opportunity to explore other metal-catalyzed cross-coupling reactions employing SEM-protected pyrroles.

scholarly journals 2-(3-Cyanopropyldimethylsilyl)ethyl as a Polar Sulfur Protecting Group

Synthesis ◽  
2019 ◽  
Vol 51 (22) ◽  
pp. 4153-4164
Author(s):  
Linda M. Bannwart ◽  
Pascal S. Rieder ◽  
Marcel Mayor
Keyword(s):  
Coupling Reaction ◽  
Cross Coupling ◽  
Thiol Group ◽  
Organosulfur Compounds ◽  
Coupling Reactions ◽  
Protecting Group ◽  
Reaction Conditions ◽  
Cross Coupling Reactions ◽  
Cross Coupling Reaction ◽  
The Stability

Organosulfur compounds are ubiquitous in synthetic chemistry, biology and materials chemistry. The reactivity of free sulfhydryls requires their masking in many synthetic strategies. To facilitate the isolation of protected thiols by chromatography, we propose 2-(3-cyanopropyldimethylsilyl)ethyl as a polar protecting group analogue of 2-(trimethylsilyl)ethyl. The masked thiophenol is obtained in two synthetically complementing ways. Either an existing thiophenol is protected, or the protected thiol group is introduced by a cross-coupling reaction. In both cases the required reagents are readily available from inexpensive starting materials. Thiol protection and thiol introduction both tolerate a large variety of functional groups and substitution patterns, and the protected thiophenols are stable toward a broad range of reaction conditions. The stability of the protected derivatives in cross-coupling reactions and the mild reaction conditions for the release of the protecting group further emphasizes the potential of the methodology.

Monodentate Trialkylphosphines: Privileged Ligands in Metal-catalyzed Crosscoupling Reactions

2020 ◽  
Vol 24 (3) ◽  
pp. 231-264 ◽  
Author(s):  
Kevin H. Shaughnessy
Keyword(s):  
Transition Metal ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Cross Coupling Reactions ◽  
Aryl Bromides ◽  
Wide Range ◽  
Sterically Demanding ◽  
Transition Metal Catalyzed ◽  
Catalyzed Reactions ◽  
Metal Catalyzed

Phosphines are widely used ligands in transition metal-catalyzed reactions. Arylphosphines, such as triphenylphosphine, were among the first phosphines to show broad utility in catalysis. Beginning in the late 1990s, sterically demanding and electronrich trialkylphosphines began to receive attention as supporting ligands. These ligands were found to be particularly effective at promoting oxidative addition in cross-coupling of aryl halides. With electron-rich, sterically demanding ligands, such as tri-tertbutylphosphine, coupling of aryl bromides could be achieved at room temperature. More importantly, the less reactive, but more broadly available, aryl chlorides became accessible substrates. Tri-tert-butylphosphine has become a privileged ligand that has found application in a wide range of late transition-metal catalyzed coupling reactions. This success has led to the use of numerous monodentate trialkylphosphines in cross-coupling reactions. This review will discuss the general properties and features of monodentate trialkylphosphines and their application in cross-coupling reactions of C–X and C–H bonds.

scholarly journals Protecting group-free, selective cross-coupling of alkyltrifluoroborates with borylated aryl bromides via photoredox/nickel dual catalysis

2015 ◽  
Vol 112 (39) ◽  
pp. 12026-12029 ◽  
Author(s):  
Yohei Yamashita ◽  
John C. Tellis ◽  
Gary A. Molander
Keyword(s):  
Small Molecules ◽  
Functional Group ◽  
Cross Coupling ◽  
Differential Protection ◽  
Coupling Reactions ◽  
Protecting Group ◽  
Cross Coupling Reactions ◽  
Aryl Bromides ◽  
Rapid Construction ◽  
Metal Catalyzed

Orthogonal reactivity modes offer substantial opportunities for rapid construction of complex small molecules. However, most strategies for imparting orthogonality to cross-coupling reactions rely on differential protection of reactive sites, greatly reducing both atom and step economies. Reported here is a strategy for orthogonal cross-coupling wherein a mechanistically distinct activation mode for transmetalation of sp3-hybridized organoboron reagents enables C-C bond formation in the presence of various protected and unprotected sp2-hybridized organoborons. This manifold has the potential for broad application, because orthogonality is inherent to the activation mode itself. The diversification potential of this platform is shown in the rapid elaboration of a trifunctional lynchpin through various transition metal-catalyzed processes without nonproductive deprotection or functional group manipulation steps.

scholarly journals Synthesis of 9-arylalkynyl- and 9-aryl-substituted benzo[b]quinolizinium derivatives by Palladium-mediated cross-coupling reactions

2018 ◽  
Vol 14 ◽  
pp. 1871-1884 ◽  
Author(s):  
Siva Sankar Murthy Bandaru ◽  
Darinka Dzubiel ◽  
Heiko Ihmels ◽  
Mohebodin Karbasiyoun ◽  
Mohamed M A Mahmoud ◽  
...  
Keyword(s):  
Emission Intensity ◽  
Binding Constants ◽  
Coupling Reaction ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Sonogashira Coupling ◽  
Reaction Conditions ◽  
Quadruplex Dna ◽  
Cross Coupling Reactions ◽  
Sonogashira Coupling Reaction

9-Arylbenzo[b]quinolizinium derivatives were prepared with base-free Suzuki–Miyaura coupling reactions between benzo[b]quinolizinium-9-trifluoroborate and selected benzenediazonium salts. In addition, the Sonogashira coupling reaction between 9-iodobenzo[b]quinolizinium and the arylalkyne derivatives yielded four novel 9-(arylethynyl)benzo[b]quinolizinium derivatives under relatively mild reaction conditions. The 9-(N,N-dimethylaminophenylethynyl)benzo[b]quinolizinium is only very weakly emitting, but the emission intensity increases by a factor >200 upon protonation, so that this derivative may operate as pH-sensitive light-up probe. Photometric and fluorimetric titrations of duplex and quadruplex DNA to 9-(arylethynyl)benzo[b]quinolizinium derivatives revealed a significant binding affinity of these compounds towards both DNA forms with binding constants ofKb= 0.2–2.2 × 105M−1.

Regiospecific Palladium-Catalyzed Cross-Coupling Reactions Using the Operational Equivalent of 1,3-Dilithiopropyne

Synthesis ◽  
2020 ◽  
Vol 52 (16) ◽  
pp. 2387-2394 ◽  
Author(s):  
Jorge A. Cabezas ◽  
Natasha Ferllini
Keyword(s):  
Coupling Reaction ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Terminal Alkyne ◽  
Copper Iodide ◽  
Reaction Conditions ◽  
Cross Coupling Reactions ◽  
Cross Coupling Reaction ◽  
Palladium Catalyzed ◽  
High Yields

A regiospecific palladium-catalyzed cross-coupling reaction using the operational equivalent of the dianion 1,3-dilithiopropyne, with aromatic iodides is reported. This reaction gives high yields of 1-propyn-1-yl-benzenes and 2-(propyn-1-yl)thiophenes in the presence of catalytic amounts of palladium(0) or (II) and stoichiometric amounts of copper iodide. No terminal alkyne or allene isomers were detected. Reaction conditions were very mild and several functional groups were tolerated.

Sonochemistry in Transition Metal Catalyzed Cross-coupling Reactions: Recent Developments

2020 ◽  
Vol 23 (28) ◽  
pp. 3137-3153 ◽  
Author(s):  
Sankuviruthiyil M. Ujwaldev ◽  
K. R. Rohit ◽  
Sankaran Radhika ◽  
Gopinathan Anilkumar
Keyword(s):  
Transition Metal ◽  
Cross Coupling ◽  
Reaction Rates ◽  
Coupling Reactions ◽  
Reaction Conditions ◽  
Cross Coupling Reactions ◽  
Recent Developments ◽  
Ultrasound Assisted ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed

: Transition metal catalyzed cross-coupling reactions have always been very important in synthetic organic chemistry due to their versatility in forming all sorts of carbon-carbon and carbon-hetero atom bonds. Incorporation of ultrasound assistance to these protocols resulted in milder reaction conditions, faster reaction rates, etc. This review focuses on the contributions made by ultrasound-assisted protocols towards transition metal catalyzed crosscoupling reactions.

scholarly journals Photo-Induced Thiolate Catalytic Activation of Inert Caryl-Hetero Bonds for Radical Borylation

2020 ◽  
Author(s):  
Shun Wang ◽  
Hua Wang ◽  
Burkhard Koenig
Keyword(s):  
Bond Activation ◽  
Reducing Power ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Reaction Conditions ◽  
Catalytic Activation ◽  
Cross Coupling Reactions ◽  
Recent Developments ◽  
Leaving Groups ◽  
Metal Catalyzed

Cross-coupling reactions are essential tools in modern synthesis of drugs, natural products and materials. The recent developments in photocatalytic radical generation have improved and expanded the classic metal-catalyzed cross coupling reactions even further. However, for sp<sup>2</sup> cross coupling reactions aryl halides or related active leaving groups, such as triflates, are required. Substituted arenes bearing strong C-X bonds remain inert to current methods. We describe now a new thiolate photocatalysis for the activation of inert substituted arenes in ipso-borylation reactions. This catalytic system exhibits strong reducing power and allows the borylation of stable C<sub>aryl</sub>−F, C<sub>aryl</sub>−O, C<sub>aryl</sub>-N and C<sub>aryl</sub>−S bonds, which are considered as chemically stable at mild reaction conditions. Our method considerably widens the available substrate scope of aryl radical precursors and we anticipate that this report will inspire new chemistry based on inert chemical bond activation.

scholarly journals Substrate Profiling of the Cobalt Nitrile Hydratase from Rhodococcus rhodochrous ATCC BAA 870

Molecules ◽  
2020 ◽  
Vol 25 (1) ◽  
pp. 238 ◽  
Author(s):  
Adelaide R. Mashweu ◽  
Varsha P. Chhiba-Govindjee ◽  
Moira L. Bode ◽  
Dean Brady
Keyword(s):  
Nitrile Hydratase ◽  
Cyano Group ◽  
Coupling Reaction ◽  
Coupling Reactions ◽  
Rhodococcus Rhodochrous ◽  
Suzuki Coupling Reaction ◽  
Enzyme Active Site ◽  
Cross Coupling Reactions ◽  
Wide Range ◽  
Cobalt Nitrile Hydratase

The aromatic substrate profile of the cobalt nitrile hydratase from Rhodococcus rhodochrous ATCC BAA 870 was evaluated against a wide range of nitrile containing compounds (>60). To determine the substrate limits of this enzyme, compounds ranging in size from small (90 Da) to large (325 Da) were evaluated. Larger compounds included those with a bi-aryl axis, prepared by the Suzuki coupling reaction, Morita–Baylis–Hillman adducts, heteroatom-linked diarylpyridines prepared by Buchwald–Hartwig cross-coupling reactions and imidazo[1,2-a]pyridines prepared by the Groebke–Blackburn–Bienaymé multicomponent reaction. The enzyme active site was moderately accommodating, accepting almost all of the small aromatic nitriles, the diarylpyridines and most of the bi-aryl compounds and Morita–Baylis–Hillman products but not the Groebke–Blackburn–Bienaymé products. Nitrile conversion was influenced by steric hindrance around the cyano group, the presence of electron donating groups (e.g., methoxy) on the aromatic ring, and the overall size of the compound.

scholarly journals Photo-Induced Thiolate Catalytic Activation of Inert Caryl-Hetero Bonds for Radical Borylation

2020 ◽  
Author(s):  
Shun Wang ◽  
Hua Wang ◽  
Burkhard Koenig
Keyword(s):  
Bond Activation ◽  
Reducing Power ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Reaction Conditions ◽  
Catalytic Activation ◽  
Cross Coupling Reactions ◽  
Recent Developments ◽  
Leaving Groups ◽  
Metal Catalyzed

Cross-coupling reactions are essential tools in modern synthesis of drugs, natural products and materials. The recent developments in photocatalytic radical generation have improved and expanded the classic metal-catalyzed cross coupling reactions even further. However, for sp<sup>2</sup> cross coupling reactions aryl halides or related active leaving groups, such as triflates, are required. Substituted arenes bearing strong C-X bonds remain inert to current methods. We describe now a new thiolate photocatalysis for the activation of inert substituted arenes in ipso-borylation reactions. This catalytic system exhibits strong reducing power and allows the borylation of stable C<sub>aryl</sub>−F, C<sub>aryl</sub>−O, C<sub>aryl</sub>-N and C<sub>aryl</sub>−S bonds, which are considered as chemically stable at mild reaction conditions. Our method considerably widens the available substrate scope of aryl radical precursors and we anticipate that this report will inspire new chemistry based on inert chemical bond activation.

PdII Immobilized on Ferromagnetic Multi-Walled Carbon Nanotubes Functionalized by Aminated 2-Chloroethylphosphonic Acid with S-Methylisothiourea (FMMWCNTs@CPA@SMTU@PdII NPs) Applied as a Highly Efficient and Recyclable Nanostructured Catalyst for Suzuki–Miyaura and Mizoroki–Heck Cross-Coupling Reactions in Solvent-Free Conditions

2019 ◽  
Vol 72 (9) ◽  
pp. 674 ◽  
Author(s):  
Maryam Sadat Ghasemzadeh ◽  
Batool Akhlaghinia
Keyword(s):  
Catalytic Activity ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Reaction Conditions ◽  
Cross Coupling Reactions ◽  
Solvent Free Conditions ◽  
Wide Range ◽  
Multi Walled Carbon Nanotubes ◽  
Catalyst Reusability ◽  
Walled Carbon Nanotubes

The new ferromagnetic nanostructured FMMWCNTs@CPA@SMTU@PdII NPs (IV) as an eco-friendly heterogeneous nanocatalyst with a particle size of ~20–30nm reported earlier by our group has been found to be very effective for Suzuki–Miyaura and Mizoroki–Heck cross-coupling reactions at ambient temperature. The procedure has been applied for a wide range of aryl halides, arylboronic acids, and alkenes. The magnetic separation by an external magnetic field, mild reaction conditions, and catalyst reusability up to four times without significant decrease in catalytic activity (reduced catalytic activity from 11 to 18% in the fifth, sixth, and seventh cycles) made the present method sustainable and economically viable for C–C cross-coupling reactions.

Sign in / Sign up

Export Citation Format

Share Document